Utilization of the SCID-hu mouse model to develop a mechanism whereby human immune responses can be studied, evaluated and manipulated under controlled conditions: specifically, to identify the antigens (and their epitapes) of the periodontopathogen, Actinobacillus actinomycetemcomitans (the etiologic agent of human localized juvenile periodontitis or LJP), that are capable of inducing responses that elevate protective immunity against this organism.